1. Field of the Invention
This invention relates to a molding which is attached to either side or the like of a car body.
2. Description of the Related Art
A conventional molding which is attached to either side or the like of a car body is configured as shown in FIG. 9 in which a molding main member 21 and retainers 22 are molded integrally together with synthetic resin (see Japanese Utility Model Publication No. 59-19639).
In this type of molding, however, there is a variation in the amount of thermal shrinkage after molding in the molding main member 21 because its thickness is not uniform. Consequently, the surface of a portion of the molding main member 21 corresponding to each retainer 22 collapses to exhibit a so-called sink mark H (shown by the two-dot chain line in FIG. 9), this tending to degrade the appearance of the molding main member. Further, a slide core must be used in connection with the retainers in the process of fabricating the molding. Consequently, the configuration of a metal mold becomes complicated, therefore causing the manufacturing cost disadvantageously high. Further, this type of molding is fabricated using synthetic resin alone. Therefore, after being attached to the car body, the molding main member 21 tends to exhibit thermal deformation (a warp) in the lengthwise direction thereof owing to the difference in the rate of thermal expansion between the car body (metal) and the molding (synthetic resin).
In view of the foregoing related art, there is a different proposal, as shown in FIG. 10, to fabricate the molding main member 21 through injection molding or by injecting synthetic resin onto the surface of an insert 23, made of a metal having a rate of thermal expansion substantially identical with that of the car body, so as to result in a substantially uniform thickness. This proposal intends to eliminate a variation in the amount of thermal shrinkage due to the non-uniformity in thickness of the synthetic resin of the molding main member 21, thereby avoiding the formation of the sink marks H on the surface of the molding main member 21, and to suppress the occurrence of thermal deformation in the lengthwise direction of the molding main member 21 due to a difference in the rate of thermal expansion.
However, even according to the foregoing proposal, the retainers must be provided in an under section of the insert 23. If this type of molding is fabricated through injection molding with synthetic resin, with the retainers previously secured to or disposed in the under section of the insert 23, so as to result in an integral member, it is difficult to remove burrs of synthetic resin formed around the retainers during the injection molding with synthetic resin, the configuration of the metal mold becomes complicated, and the cost of manufacturing of the molding increases.